1. Field of the Invention
This invention relates to a rhinological diagnostic device (hereinafter referred to as the nasal test sheet) which is used in diagnosing an inflammation in the nasal cavity or monitoring the degree of healing of the inflammation.
2. Brief Description of the Prior Art
In clinical otorhinology, it is common practice to measure the nasal air flow or the difference in air flow between the right and left nostrils of patients with nasal catarrh, acute rhinitis or other inflammation of the nose. While, for detecting inflammatory lesions in the nasal cavity, nasopharyngoscopy is commonly used to visually examine the nasal meatus and nasopharynx, the nasal air flow is generally measured using the more expedient rhinomanometric device, known as a Gratzel sheet, which is made of glass or stainless steel. Diagnosis using the Gratzel sheet is based on the image of water vapor formed by expired air on the cold surface of the sheet positioned immediately beneath the subject's nose. Though it is thus expedient, the Gratzel sheet has the following disadvantages.
(a) Since glass or stainless steel is high in thermal conductivity, the temperature differential between the sheet and expired air leads to a variation in the amount of water vapor deposited by the expired air.
(b) Since the water vapor deposited on such a rhinomanometric test sheet is dissipated almost instantly irrespective of the ambient atmospheric conditions, an accurate quantitation of such deposits is technically difficult.
(c) The water-vapor image of expired air is not sharp enough and, moreover, disappears in an instant so that it cannot be photographed. It is an object of this invention to provide a nasal test sheet which is free of the above-mentioned disadvantages of the prior art rhinomanometric device and, in addition, has the following novel features.
(a) The temperature of expired air from the subject's nasal cavity which impinges on a thermochromic liquid crystal sheet can be estimated from the color change of the sheet.
(b) The color image produced by expired air on the thermochromic liquid crystal sheet persists for a period of several seconds.
(c) The color image is sharp.
Particularly the feature (a) is quite unique. Thus, it is known that when an inflammation is induced by some cause or other in the human body, the local circulation increases and the inflammation site assumes a temperature higher than that of the surrounding region. In fact, in cases of rhinitis, the temperature of expired air is higher than normal. On the other hand, in allergic rhinitis which has been gathering attention in recent years, curiously the temperature of expired air may be lower than normal dispite the presence of an inflammation. The nasal test sheet of this invention enables the professional measure the temperature of the patient's expired air which could not be ascertained before.
Thus, by utilizing a liquid crystal, the nasal sheet of this invention not only provides an opportunity to determine the temperature of expired air which cannot be known with the conventional rhinomanometric sheet but also provides a visual image of expired air which lasts a sufficient time to permit photographing. These are very remarkable features of this invention.